1. Field of the Invention
The present invention relates to a pixel circuit of a high-speed CMOS image sensor.
2. Description of the Related Art
In a general pixel circuit of a CMOS image sensor, signal charges are stored and read, then signal charges are initialized (reset) for each horizontal line. Since the start timing of reset and the start of signal charging differ depending on the horizontal line, distortion occurs in an image which has a large movement. A CCD image sensor, on the other hand, can reset all the pixels at the same time and start signal storing at the same time. This is called an “electronic shutter operation” or “global shutter”.
Conventional methods for performing an electronic shutter operation using a CMOS image sensor are a method disclosed in U.S. Pat. No. 5,986,297, “Color active pixel sensor with electronic shuttering, anti-blooming, and low cross-talk”, and a method disclosed in Kokai publication No. 2000-504489 (cf. WO 97/28558), “Active pixel sensor array comprising electronic shutter operation”.